Since the consumption math mechanism is based on the values of the ignition sensor, check its properties and operation. You may not have this sensor created or there may be 0 l/h indicated for the fuel consumption in its properties.

What if the unit doesn't have ignition?

You may use one of the approaches described below.

Variant 1

Create a virtual ignition sensor. We recommend that you use average speed (speed+#speed)/const2 as its parameter.

Variant 2

Even if you haven't installed an ignition sensor in the unit or are not sure of the name of the parameter that responds for the ignition, in the parameters of the device there may be some characteristic that corresponds to the operation of the engine. To use it, compare two messages from the unit: one — when the ignition the most probably off; the other — when it's on.

Example.

During a long time interval the unit sends approximately the following set of parameters:

hdop=1, odo=0, adc2=2.0475, adc12=1037, c1=0, c2=0, c3=0, c4=0, mcc=260, mnc=2, lac=56720, cell_id=43811, ta=1,
gsm_lvl=55, total_fuel=407154, can_fls=101, can_taho=4797, can_engine_hrs=230420, can_mileage=137603392, engine_temp=123,
srv_dist=0, j1939_air_temp=9072, J1708_eng_hrs=230420, J1708_fl_used=430282, J1708_fl_lvl=101, I/O=80/0

While moving at some speed — approximately the following:

hdop=1, odo=847.358764648, adc2=2.3595, adc12=1117, c1=0, c2=0, c3=0, c4=0, mcc=260, mnc=2, lac=56720, cell_id=60167, 
ta=1, gsm_lvl=71, total_fuel=407178, can_fls=101, can_taho=9940, can_engine_hrs=230447, can_mileage=137609550, 
engine_temp=124, srv_dist=0, j1939_air_temp=9353, J1708_eng_hrs=230447, J1708_fl_used=430307, J1708_fl_lvl=101, I/O=d1/0

Straight before the start of the movement, as a rule, the ignition turns on:

hdop=1, odo=0, adc2=1.4937, adc12=895, c1=0, c2=0, c3=0, c4=0, mcc=260, mnc=2, lac=56720, cell_id=60268, ta=2, 
gsm_lvl=64, total_fuel=407166, can_fls=100, can_taho=996, can_engine_hrs=230439, can_mileage=137605711, engine_temp=120, 
srv_dist=0, j1939_air_temp=9369, J1708_eng_hrs=230439, J1708_fl_used=430295, J1708_fl_lvl=100, I/O=80/0

Discard the parameters that are obviously imprecise: hdop (precision), adcN (it's difficult to determine the regularity), odo (relative odometer in meters), mcc mnc cell_id and lac (LBS data section), gsm_lvl (the level of the GSM signal), etc. The parameter J1708_eng_hrs for this unit seems the most probable, as it doesn't change during the night parking. As a rule, it is also possible to use pwr_ext. Is the ignition is digital, you can follow the values' changes in the block 'I/O =' (see more details in the section 'Inputs and Outputs').

Variant 3

If you have already connected the ignition, find out its parameter by means of the method described above or from the manual of the manufacturer.

Why does mathematical calculation show enormous values?

Possible reasons:

1. In some cases the system may consider that during the interval with no messages from the unit its ignition was on. Adjust the default value '0 seconds' on the option 'Maximum interval between messages' on the 'Advanced' tab of unit properties. The influence of the option on the fuel calculation is described in the documentation.
   
2. Several engine efficiency sensors can be created. Check up their values. The easiest way to evaluate it is to create in a report a simple chart with one of the curves 'Fuel consumption by math'.
   

How should I calculate the coefficient and fill in the calculation table, if I want to get the consumption equal to 33 liters per 10 km in the table?

The algorithm doesn't show a number in the report as it used to be, but analyses the time between messages. Therefore, you can indicate the calculation method that is convenient for you. For example, in the following way you can get the number as approximate to the previous calculations as possible:

1. Create an ignition sensor with the parameter of average speed between two points (speed+#speed)/const2. If you already have one, there is no need to create another. Put '3.3' in the option 'Consumption, l/h' in the sensor's properties (generally, according to the majority of the automakers, the consumption during idling per hour is approximately equal to the consumption per 10 km, i.е. 33/10 = 3.3 in this case).
   
2. Create an engine efficiency sensor. Its value will show how many times higher (o lower) the fuel consumption of the unit is supposed to be relatively to the consumption during idling. Use the parameter (speed+#speed)/const20.
   

Anyway, it doesn't coincide: on some intervals the consumption is more, on some — it is less. The final result is almost correct, but not completely.

The GPS mileage in the report takes into account the curvature of the planet, the altitude, the latitude and the longitude. The number obtained in the consumption above counts the mileage as a ratio of speed to time. Consequently, the more often and the more accurate is the data sent by the unit, the more precise the result will be. If there is an ignition sensor, the number will be slightly higher than for the 'virtual' ignition (according to average speed), since idling will also be taken into account.

How to determine the fuel consumption, if I know how much the object consumes in the city, and how much — outside it?

Let us suppose that the fuel consumption in the urban cycle is 10 l/100 km and 7 l/100 km — in the suburban cycle.

1. Create an ignition sensor (as in the example above) and set 1 l/h for the consumption during idling.
   
2. The average consumption in the urban cycle is 36 km/h, in the suburban — 80 km/h.
   
3. The unit will cover the distance of 100 km driving at a speed of 36 km/h in 2.8 hours. 10 l / 2.8 = 3.57. Let us calculate the value of the increasing coefficient when moving in the city: 3.57 / 1 (idling) = 3.57.
   
4. As a result of a similar calculation for the suburban cycle, we obtain the coefficient equal to 5.6.
   
5. Create an engine efficiency sensor, taking into account the fact that the unit cannot consume less fuel than during the idling, and that it is stationary before the beginning of the movement. As a parameter we use the average speed (speed + # speed) / const2 and fill in the calculation table (manually or using the calculation table wizard):
   

Note that the last pair of points is how the system calculated before (the fuel consumption was considered constant for a speed above 80 km/h). You cannot use this method and change the set of points. Also '3' in this example is the minimum speed from the unit's trip detector, consequently, this parameter can be different for your unit.

Result: in our example the average consumption has been calculated for the unit. It has been calculated relative to the speed and time between messages and taking into account the values of the vehicle operation.

Where are such consumption values taken from? How does the algorithm work?

During the mathematical calculation the fuel consumption is computed separately for each pair of messages.

The following algorithm is used:

1. The status of each engine sensor (engine ignition, absolute and relative engine hours sensors) in the current message is determined.
   
2. For the operating sensors the values indicated in the field Consumed, l/h of their properties are summed.
   
3. The values of the engine efficiency sensors are calculated.
   
4. The received values are summed according to the formula k1 + (k2 - 1) + (k3 - 1) + … + (kn – 1). In that way the coefficient is formed. If the sum of the coefficients is less than 0 or invalid, the total coefficient will be 1.
   
5. To determine the current fuel consumption of the unit, the value from the point 2 is multiplied by the value of the point 4.
   
6. The value from the previous message till the current one is multiplied by the value from the point 5.
   
7. The consumption for each message pair for the indicated interval is summed and in that way the fuel consumption is determined by consumption math.
   

Where is the consumption by rates?

Now this option is in the 'Advanced' tab.

How is the seasonal coefficient calculated now?

As a rule, the seasonal coefficient supposes increased fuel consumption. For instance, the consumption in winter is 30% higher than in summer. Let us suppose, that the winter in your climate is from December, 1 to March, 1.

1. Create an engine efficiency sensor with the parameter time:d.
   
2. Find out which numbers of the day in the year do your dates correspond to. High precision is not obligatory: a year may be a leap one and the season itself may be longer or shorter. For the period indicated above, for example, the numbers are '334' and '59' approximately.
   
3. Create a calculation table as seen on the screenshot below.
   

time is the parameter that is present in any message from any device, and the system will calculate the number of the day automatically on its basis. In that way, as the season starts, 30% will automatically be added to the fuel consumption.

How can I make the calculation precise and not approximate?

A more accurate result can be obtained if there is, for example, an ambient temperature sensor by means of calculating an increase in the norms in certain conditions.

What for were these features introduced?

They are necessary for adaptive calculation of fuel data taking into account different conditions: various types of implements, temperature regimes, operating conditions, vehicle mileage and its technical state, several fuel consumers on the same unit, acceleration/braking, engine revolutions.